Electrical measuring instrument.



P. MAcGAHAN. ELECTRICAL MEASURING INSTRUMENT. APPLICATION FILED MAY I."|9 .3.

LQQKQfl Patented May 22, 1917.

. 1. 'Fig. 3 is "the. .core and dieeast UNTED emaane ,PAENT, FlFlCE.

Application filed May 1, 1913. Serial No. 764,867.-

To all whom it may concern:

Be it known that I, PAUL MAcGAuAma citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Electrical Measuring Instruments, lowing is a specification.

My invention relates to electrical measuring instruments and particularly to novel features of construction thereof. i

The object of my invention is to provide an electrical measuring instrument with bearings and pole pieces which are simple and inexpensive to construct.

In electrical measuring instruments, the permanent magnet pole pieces are usually accurately machined and centered to receive the permanent magnet yoke and the core of the rotatable element. The cost of machining such pole pieces is high and requires a great amount of skill. The bearings of the rotatable armature element of electrical measuring instruments, as heretofore constructed, were usu lly also expensive to manufacture. v I 1 My invention illustrated in the. accompanying drawings in which Figure 1 is a plan view of the assembled instrument. Fig. P is a section on the line IIIT. of Fig.

ings, partially in section. F ig. 4 is a perspective view of one of the pole pieces. Fig. 5 is a perspective viewof the magnetic core of the instrument without its supporting member. Fig. 6 is a front elevation of the die-cast pole pieces and their housing. Fifi 7 is a top plan view Fig. 6. Fig. 8 is a sectional view on the line VIII-VIII ofFig. 6. Fig. 9 is a view of bearing supports. Fig. 10 1s a sectional viewon the line X- X of Fig. 9." Fig. 11 is a top plan View of the 12 is a sectional of F ig. 10. Fig.

parts shown in Fig. 9. Fig. view/en the line XII- XII l3 a plan view of a portion of the rotatable element the support for its pointer.

{Referring to the drawings, the electrical measuring instrument I compriscsa permanent magnet 2, field pole pieces 5-, and 4- Specification of Letters Patent.

of which the lol-.

a detail'view of one of the bearrecess 15 which extends of the parts shown in Patentedlllfay 22,

which are fastened to the frame by screws 5 and 6, a rotatable armature 7 .a'pointer 8 and a core 9 so disposed that when a current flows tlmmgh the armature. the latter turns around'the core 9 and,with the aid of the pointer S, indicatesthecorrect reading, of the,instruinenton a scale (not shown). 2 1

Having described, 7 tion of the instrument, a more explicit description of the novel features of my. invention will be given. Rectangular bodies of steel (not shown) with grooves for anchoring purposes and then are cut into two parts to form two pole pieces like the pole piece 3 shown in Fig. 4.

Two such pole pieces are centered' on a die' are drilledand provided in general, the opera- .7 and (l. Thenovelty of this part of my invention is that, with the so-called diecast pole chine work after casting, mg and chcapenmg the pieces, accurate 'cen tel-mg oi the .pieces may be had \VltllOlIt ma-' thereby sunplify- The housing or dic-cast frame 10 has feet j 11 and 12' for supporting the instrument dial (not shown). andalsoa pro ]ei-tion 13 for supporting the instrument mechanism from the case I (not shown). The die-cast frame or housing 10 IS provided with a slot 14 in its top atone end and'wlth an inside the housing and for tluu-learmu-e betwecniield pole pieces, as shown in l igsjfi, 7 and S. i The housing '10 is tapped for receiving screws at points l6, 17,. 18,19,20 and 21, and the screw holes 20 and 21 are extended through a member 22 which is die the housing into cast to the core 9 around which the armature 7' turns.

The member 22 is inserted in the slot it and the recess I5 audit is fastened to the-housing IQ by screws :53 and 24 that are inserted in screw holes 20 and 21, respectively. The member 22 has arms 25-and 26 east integral with its rcs lective ends, to rve as supports for the armature 7, the

the. entire lengthof' adjoins the opening left arm being provided with two screw holes 27 and 28 and the arm 26 with one screw hole 29.

tered therein to coiiperate with a bearing jewel 38 that is cemented to the armature through a hole in a metal strip 37. The metal strip 37 is also cemented to the armature. I

Springs 39, and 40 are employed, in accordance with the usual practice, to control the deflection of the movable element cific type of instrument, since it 7 and the resulting indication of the pointer so that they shall be proportional to the current of electricity flowing. The respective ends of the spring 39 are fastened to a stationary member 41 and to the armature 7, and the corresponding ends of the spring 40 are fastened to a stationary member 4:2 and to the armature.

T he member 22 is used both as a support for the armature 7 and as a support for the magnetic core 9 about which the armature turns. The core 9 forms a path for the magnetic flux which passes through the armature from one pole piece to the other.

The bearing screws 30 and 35, having the steel pivotpins 31 and 36, respectively, are disposed in such a manner that they may beturned to conform to the spacing of the jewels or to release the armature element. The instrument members that are supported by the housing 10 may be remove withdrawing the screws 23 and 24 and,

after such removal, the armature 7 and itsbe detached by connected elements may loosening, either the screw screw 35.

The means for uniting the armature, the bearing jewels and the pointer insure a light, inexpensive and durable instrument but it must be understood that a cement which will not deteriorate with age and which will remain intact under all climatic conditions should be employed.

I do not limit my invention to any speis equally applicable to the bearings of any lightweight moving elements, and the die-cast field poles are equally applicable to perma- 30 or the nent or electro-magnets, of any form and adapted to any use.

I claim as my invent1on: 1. In an electrical measuring instrument,

eaf/ace the combination with an armature and fieldmagnet pole pieces, of a non-magnetic housing disposed around all sides thereof except the sides adjacent the armature and the sides opposite thereto, a magnetizablc core'memher having a non-magnetic supporting member on one side thereof, and means for rcmovably attaching said supporting member to the housing.

In an electrical measuring instrument, the combination with an armature and accurately centered field-magnet pole pieces, of a non-magnetic housing disposed around all sides thereof except the sides adjacent the armature and the sides opposite thereto, a magnctizable core member, a supporting member secured to the core member, and a single means for centering the core member with respect to the field-magnet pole pieces.

. In an electrical measuring curatcly centered field-magnet pole pieces, of a non-magnetic housing disposed aroun all sides thereof except the sides adjacent the armature and the sides opposite thereto, and a maguetizable core member removably attached at one side to said housing.

instrument, the comb1nat1on with an armature and ac- 4. In an electrical measuring instrument,

the combination with an armature, pole pieces having concave surfaces adjacent the armature, and a permanent field magnet, of a housing disposed around all sides of the pole pieces except the concave surfaces and the sides opposite thereto, and means for removably securing the permanent magnet to the sides of the pole pieces opposite to the concave surfaces.

5. In an electrical measuring instrument, the combination with accurately centered field-magnet pole-pieces having substantially plane outer faces, and a permanent magnet operatively secured to the plane outer faces thereof, of a non-magnetichousing secured to all sides of said pole-pieces except the outer faces and the sides opposite thereto, a magnetizable core member, a supporting member secured to said. core member, and means for centering the core member with respect to the pole-pieces.

6. In an electrical measuring instrument, the combination with accurately centered field-magnet pole-pieces severally having a substantially concave and a substantially plane opposite face, and a permanent magnet operatively secured to the plane faces thereof, of a non-magnetic housing secured around all sides of the pole-pieces except those having the concave and plane faces.

7. In an electrical measuring instrument, the combination with accurately centered field-magnet pole-pieces severally having a substantially concave and a substantially plane opposite face, and a permanent magnet operatively secured to the plane faces In testimony whereof, I have hereunto thereof, of a non-magnetic housing secured I subscribed my name this 24th day of April 10 around all sides of the pole-pieces except 1913.

those -having the Concave and the plane v 3 faces, a magnetizable core member, and PAUL MACGAHAN' means secured to the core member fcpsup Wltnessesz porting the same from the housing at a Tnos. S. PUKERUD,

single point between the pole-pieces. B. B. HINEs. 

